Bishkek (AKIpress) - China's government released a yearslong study that shows nearly one-fifth of the country's farmland is contaminated with toxic metals, Charlotte Observer reported.

The report nickel and arsenic as the top contaminants. It adds to widespread doubts about the safety of China's farm produce and confirms suspicions about the dire state of its soil following more than two decades of explosive industrial growth, the overuse of farm chemicals and minimal environmental protection.

It also points to health risks that, in the case of heavy metals, can take decades to emerge after the first exposure. Already, health advocates have identified several “cancer villages” in China near factories suspected of polluting the environment where they say cancer rates are above the national average.

The soil survey was conducted from 2005 until last year, and showed contamination in 16.1 percent of China's soil overall and 19.4 percent of its arable land, according to a summary released late Thursday by China's Environmental Protection Ministry and its Land and Resources Ministry.

China's leaders have said they are determined to tackle the country's pollution problem, though the threat to soil has so far been overshadowed by public alarm at smog and water contamination. However, recent scandals of tainted rice and crops have begun to shift attention to soil.

A key concern among scientists is cadmium, a carcinogenic metal that can cause kidney damage and other health problems and is absorbed by rice, the country's staple grain.

Last May, authorities launched an investigation into rice mills in southern China after tests found almost half of the supplies sold in Guangzhou were contaminated with cadmium.

In early 2013, the newspaper Nanfang Daily reported that tens of thousands of tons of cadmium-tainted rice had been sold to noodle makers in southern China since 2009.

The summary of findings gave no detailed breakdown of contamination by region. It said most of the contaminated soil had levels of pollutants ranging from just above the allowable limit to double the limit, while for 1.1 percent of the country's soil the contaminants were at five times the safety limit or more.